The proposed research for the coming year will include investigations of the young infant's ability to process phonetic contrasts and investigations to determine the nature and properties of feature detectors assumed to underlie the perception of speech. With regard to the former, studies will be undertaken to ascertain the role of at least two cues in the perception of contrasts based on place of articulation: the initial bursts and the second-and third-formant transitions. Other studies are planned which will attempt to define the minimal acoustic information necessary to initiate a linguistic (i.e., phonetic feature) analysis of acoustic information in infants and adults. With regard to the latter studies, current investigations will be continued in the attempt to define the nature of the acoustic information which is adequate for the excitation of the proposed feature detectors. These studies will examine higher order information such as the relation of the formant transitions to the vowel quality and the relation of voicing information to vowel quality and place information. Theoretical descriptions of the mechanisms underlying speech perception in the infant and adult listener will be undertaken. These descriptions will attempt to determine whether a feature detector theory can accomodate the known complexities of human speech.